Many forms of microelectronic devices, such as IC (integrated circuit) packages, include a semiconductor package substrate or similar structure (such as a redistribution layer (“RDL”), interposer, etc.). All of such structures are generically referred to herein as “substrates” for purposes of the present disclosure. In many examples, manufacturing such substrates includes forming one or more build-up layers over an underlying structure (such as a substrate core, a semiconductor die, reconstituted wafer, etc.). Such build-up layers commonly include a dielectric, with a conductive material extending over the dielectric and forming contacts through the dielectric (such as micro-vias) to a conductive structure below (such as another conductive layer, a contact pad, through core contact, etc.).
In the forming of such substrates, it is often desirable to form the conductive structures through electroless deposition of the metal conductor (and via) material. Such electroless deposition, however, may require deposition of a seed layer upon which the electroless metal can be deposited. In many examples, the seed layer is sputtered onto the patterned build-up dielectric material, and the electroless metal is deposited to form the conductive layer and vias.
Photoimageable dielectric film (“PID”) offers many advantages in forming structures such as build-up layers. However, conventional photoimageable dielectric film presents challenges relative to adhesion of metallic materials, such as metal seed layers, to the films.